Method of and apparatus for producing coated metal objects.



J. I. MON N OT. METHOD OF AND APPARATUS FOR PRODUCING COATED METAL OBJECTS.

APPLICATION FILED JULY2, 1909.

Patented Oct. 11, 19.10.

WITNESSES v/m a. M27.

im Iran is'ra'rss PATENT ora ion.

JOHN F. MONNOT, OF NEW YORK, N. Y., ASSIGNOR T0 DUPLEX METALS COMPANY,

OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

METHOD OF AND APPARATUS FOR PRODUCING COATED METAL OBJECTS.

Specification of Letters Patent. Patented 001;. 11, 1910.

Application filed July 2, 1909. Serial No. 505,698.

To all whom it may concern:

l 3e it known that 1, JOHN F. Momvor, a citlzen of the United States, residing at New York, in the county of New York and State of New York, have invented a certain new and useful Method of and Apparatus for Producing Coated Metal Objects, of which the following is a specification.

My invention relates to methods of and apparatus for producing coated metal ob- JQCtS, particularly compound ingots comprising unlike metals weld-united, and consists in means whereby a billet or object to be coated may be heated to a hi 'h temperature while immersed in a bath 0 flux or like fused protective material, and may be transferred to a mold while still submerged in such protective material, and then may have a layer of molten metal cast about it and united to it the metal so cast solidifies.

My invention further consists in the proccomprising the heating of an object to be coated, under protection of an enveloping bath of fused protective material. transferring the object while still so enveloped to a suitable mold, and casting a body of molten metal or other suitable material into said mold and against the surface of the heated object and'causii'lg the metal so cast to solidify against such object; the metal so cast being east through a deep body of the molten protective material within the mold and displacing such material, the latter therefore serving as a wiping material for the molten metal, whereby the molten metal as cast is purified and freed from entrained and occluded gases, oxid impurities, etc.

I will now proceed to describe my invention with reference to the accompanying drawings, illustrating two forms of apparatus embodying the apparatus portion of my invention and adapted for carrying out the process, and will then point out the novel features in claims.

In said drawings: Figure 1 shows more or less diagrammatically, a vertical longitudinal section of a furnace of the open hearth type. having a hearth of peculiar form adapted for carrying out the herein described process. Fig. 2 shows a transverse section of such furnace, and shows in connection therewith a mold and means for handling the mold. Fig. 3 shows a transversesection of the mold on the line of 2.

In the production of compound metal ingots, comprising unlike metals united, and particularly in the production of ingots consisting of a ferrous metal, such as iron or steel, surrounded by and welded to a layer of non-ferrous metal, such for example as copper, it is very important to maintain on the billet to be coated a clean metallic surface. It is also necessary or advisable, in most cases, that this billet shall be heated to a moderately high temperature, at least, before the molten metal contacts with it to insure the maintenance of a reactive temperature at the time of union between the two metals; and it is further desirable that this molten metal shall be cast under such conditions that all entrained or occluded gases in the metal shall be removed, also oxid impurities, etc., and that gases and other impurities shall not gain access to the zone between the two metals at the time of union.

In former patents I have described processes wherein a bath of the desired coating metal is maintained in the desired molten condition, the metal object to be coated is immersed in this bath and a portion of the molten metal surrounding said object is segregated and caused to solidify on said object. It is quite difiicult, however, to maintain a large bath of molten metal in the desired condition of extreme purity, particularly when such metal must be maintained at the very high temperature which in most cases is required in order that a perfect weld union may result; for-at such high temperature the metal is particularly subject to contamination from furnace gases, air, etc., and it is almost impossible to prevent such contamination altogether. And the dipping or immersing operation is apt to permit aerial contamination of either the coating metal or the core. Furthermore, molten metals at such high temperatures seem to have a direct solvent action on other metals inserted into them, and so are liable to cumulative contamination by contact with the objects to be coated. The apparatus herein described provides means whereby the billet or other object to be coated may be protected thoroughly against contamination, and means whereby only that quan tity of molten metal actually required to form the coating is brought into actual proximity to the object to be cast, and whereby such molten metal may be chilled almost immediately after. casting and the effecting of union, to a temperature sufiiciently low to practically obviate solution nace having a'roof 1, ports 2, 2 for the entrance and exit of the heating gases, and a deep hearth 3 adapted to contain objects to be coated and a body of fused protective material of suflicient depth to completely submerge said object. The ducts 2, 2 are partially separated from the hearth by bridge walls 4, 4:, so that the flame gases are forced to travel along the under side of the roof of the furnace, the heat being sunned down through the layer of fused protective material contained in said hearth. Suitable doors 5, 5 are provided at intervals in the sides of the furnace, through which doors implements may be inserted for rolling the objects within the furnace along the hearth, and through which such objects may be introduced into the furnace. The hearth is provided, near one end, -with a slight dip or trough 6, and near such gutter with a deeper dip or trough 7 pitched toward an opening 8 (Fig. 2) in one side of the furnace; and between these gutters 6 and 7 is a slight rise 9. A sliding valve 10 is provided for closing opening 8; suitable means, for example, a rack 11, pinion l2 and hand wheel 13, being provided for operating said valves.

A mold 14 is adapted to be brought into registry with opening 8 and to fit closely into such opening, so that molten material may not escape in quantity between the furnace and 'the end of the said mold. This mold is, shown mounted upon a movable pedestal 15, means, such as gearing 16 and a hand wheel 17, being provided for tilting such mold. Said mold may have a removable bottom plate 18, by the removal of which bottom plate passage of flame gases from a suitable burner (not shown)- through the mold may be permitted when the mold is removed from the furnace, for the purpose of heating it. By removing the bottom plate, it is possible to remove the cast ingot from the lower end of the mold, or, alternatively, to introduce the plunger of a hydraulic press through that end of the mold to force the cast in ot out through the opposite end of the mo (1. The mold is further provided with a jacket space, 19, through which a cooling fluid or gas may be circulated for quick cooling of the molten metal. The bottom plate 18 of the mold is provided with a tapering centering recess 20 for automatically centering the lower end of the billet, and suitable centering means may be provided near the upper end of the mold also. The mold is shown provided with a lining 21 which may be renewed from time to time, in order to keep the di ameter of the moldpractically constant This lining may be of crucible mixture, homogenized graphite, etc.

The operation of this apparatus, and the method of carrying out the process, are as follows:

The hearth of the furnacehaving been charged with a suitable quantity of protective material, (one material suitable for the purpose is a mixture of borax and sodium silicate; but furnace slags are also suitable and are somewhat cheaper) and the furnace having been heated to a proper temperature by the circulation of heating gases through it, anumber of billets, designated in the drawings by numerals 22, are placed upon the hearth of the furnace, being submerged in the protective material therein and so protected against contamination by the furnace gases; while at the same time the surfaces are cleaned by the solvent action of the fused protective materiah When the billets have been heated to a proper temperature the mold let is moved up with its end against the opening 8, and one of the billets is. rolled down into the trough 6; the valve 10 is then opened, so that the mold fills with the molten protective material and the billet within trough 6 is then rolled trough 7, another billet being rolled into trough 6; and the billet rolled into trough 7 at once slides out of the opening 8 into the mold, displacing the greater part of the molten protective material then in the mold and causing the same to flow back into the furnace. The valve 10 is then closed and the mold moved back and tilted upright, the billet is centered in the mold, if necessary, and then molten coating metal is poured into the mold, such molten coating metal passing down through the protective material in the mold, which protective material then serves as a wiping material to free it of surface impurities. The molten metal is then permitted to solidify and as soon as sufficiently solid, the ingot so produced is removed from the mold, and'tho let. In the meantime, however, still other molds may have been moved up into position against the furnace and may have received other billets and had other ingots cast in them.

It is to be observed that the entire operation thus described takes place withoutexposure of-the surface of the object to be coated, to contact with air or other contaminating gases; and that the molten metal, as cast, is purified by passing through the molten wiping material, and so is freed from entrained and occluded gases, oxid impurities, etc, a dense, uniform,close-grained coating metal being thereby assured. Likewise, it is not necessary to maintain large quantities of molten coating metal large enough for the submergence of a billet at a high temperature for a long time.

The molten coating metal is preferably cast at the very high casting temperature referred to by me in prior patents as the supermolten temperature, and when so cast it unites with the surface of the billet, upon contact therewith, producing a welded union. Since the supermolten coating metal tends to dissolve the metal of the billet, the mold is preferably provided with a acket 19, and through this jacket cooling water or other suitable cooling medium is circulated as soon as cont-act and union between the molten metal and the billet have-taken place. Thereby the molten metal is chilled quickly to a temperature such that its tendency to dissolve the metal of the billet quickly practically disappears.

For operation requiring the use of supermolten metal, the process above described has the great advantage that it is notv necessary to maintain a considerable quantity of molten metal at the supermolten temperature for a long time. Instead it may be maintained at ordinary casting temperature, in which condition it is not particularly subject to contamination by the-air, furnace gases, etc., until it is about to be needed, and may then be heated quickly to the desired higher temperature, and immediately poured into mold 21.

I have shown the furnace provided at its ends with ports normally closed by plates 24, and have shown, adjacent to these ports, burners 23. These burners may be used for heating up' the furnace, the plates 24 being removed, or, the furnace may be worked by means of these burners, instead of by the ordinary regenerators and gases heated therein.

Without restricting myself to any particu lar materials to be coated or to be used as coating metals, in the. described process, I will state that my said process is particularly intended for coating ferrous objects, such as iron with non-ferrous high melting .metals, such as copper and silver, and for producing ingots in which the core or base metal (ferrous metal) and the coating metal (.nonferrous metal) are weld-united. Such weld united unlike metals I commonly term clad metals.

In a companion application Ser. No. 505,699, filed July 2, 1909 I have claimed a process comprising heating a metal article to be coated while it is submerged in a bath of fused protective material, transferring such heated object without exposure of it above the surface of such protective material, into a suitable mold, and casting molten metal into such mold and into contact with the surface of such object, and permitting such molten metal to solidify against such surface.

Therefore I do not claim said process in this application. In said companion application I have also claimed apparatus comprising a vessel adapted to contain an object to be coatedand fused protective material enveloping such object, said vessel having an opening adapted for regis try of a mold therewith; therefore I do not claim such invention broadly herein.

In some cases it is desirable to provide the object to be coated with a thin welded on coating of an unlike metal, before such obj ect is passed into the mold, and is contacted with the main body of molten coating metal. Such metal of the thin coating, which then becomes an intermediate metal in the final product, may either be the same metal as the metal of the thin coating, or it may be different material, for example,- when the metal of the main coating is to be brass or bronze, the metal of the intermediate coating will be copper. Such intermediate coating nay be applied readily in the apparatus above described, the pool of metal to form the thin coating being contained in the shallow trough 6. The billet, as it is rolled through such trough, cont-acts with the coating metal (the latter usually at the supermolten temperature) in this trough, and hence is coated by it. Or, the intermediate coating may be applied to the billet, while the latter is passing through this trough 6, by passing an electric current from the pool of molten metal in said trough to the billet, using the latter as a cathode.

In my application Sr. No. 469,016, filed December 23, 1908, I have claimed a process of coating metals comprising making the object to be coated a cathode in a bath of fused electrolyte containing a dissolved ductile high melting different metal, such bath maintained at a temperature above the melt-- ing point of the coating metal.

What I claim is 1. A method of producing coated metal objects, which comprises heating a metal article to be coated on the hearth of a furnace and under cover of a bath of fused protective material, connecting to such furnace a mold and allowing same to fill with such protective material, and then passing said object into said mold and displacing a portion of the protective material in the mold back into said furnace, disconnecting the mold from the furnace and casting molten metal into the mold and into contact with the surface of said object, and permitting such molten metal to solidify against such surface.

2. Apparatus for forming coated metal objects comprising a furnace having a hearth adapted to contain obj ects to be coated and containing a pool of fused protective material enveloping said objects, said furnace having a port opening into its hearth space and adapted for registry of a mold therewith, and means for closing said port.

3. Apparatus for forming coated metal objects comprising a furnace having a hearth adapted to contain objects to be coated and containing a pool of fused protective material enveloping said objects, said furnace having a port opening into its hearth space and adapted for registry of a mold therewith, means for closing said port and molding apparatus comprising a mold adapted for registry with said port and supporting means vfor the mold adapted tov tilt same to an inclined position for registry with said furnace port and to tilt same to an upright position for receiving molten metal.

41. Apparatus for forming coated metal objects comprising a furnace having a hearth adapted to contain objects to be coated and to contain a pool of fused protective material to envelop such objects, said furnace having a depression in one portion of its hearth adapted to receive one of such objects and having a port registering with such depression.

'5. Apparatus for forming coated metal objects comprising a furnace having a hearth adapted to contain an object to be coated, and to contain a pool of fused protective material enveloping such objects, said hearth having two adjacent depressions, one deeper than the other and separated from that other by a slight rise, and a port communicating with such deeper depression.

6. Apparatus for forming coated metal objects comprising a furnace having a hearth adapted to contain objects to be coated and to contain a pool of fused protective mate rial to envelop such objects, said furnace having a depression in one' portion of its hearth adapted to receive one of such objects and having a port registering with such depression, and means for closing said port.

7. Apparatus for forming coated metal objects comprising a furnace having a hearth adapted to contain an object to be coated and to contain a pool of fused protective material enveloping such objects, said hearth having two adjacent depressions, one deeper than the other and separated from that other by a slight rise, and a port communicating with such deeper depression, such deeper depression being inclined.

8. Apparatus for forming coated metal objects comprising a furnace having a hearth adapted to contain an object to be coated and to .contain a pool of fused protective material enveloping such objects, said hearth having two adjacent depressions, one deeper than the other and separated from that other by a slight rise, and a port. communicating with such deeper depression, such deeper depression being inclined, and means for closing such port.

9. Apparatus for use in forming coated metal objects comprising a mold, a support therefor, adapted for tilting such mold from an upright to an inclined position and means for conveying a heated metal objectinto said mold without exposure to air.

10. Apparatus for use in formiugcoated metal objects, comprising a vessel adapted to contain an object to be coated, one end of such vessel adapted to form a joint with the port of a furnace, and a support for said vessel adapted for tilting said vessel from a vertical to an inclined position.

In testimony whereof, I aflix my signature, in the presence of two witnesses.

JOHN F. MONNOT. Witnesses:

H. M. MARBLE, FRANK E. RAFFMAN. 

